System and method for detection of dental tartar

ABSTRACT

A dental tartar detection system ( 10 ), especially for detection of subgingival tartar (S), comprises a probe ( 12 ) adapted to be displaced along a tooth (T) an illumination system ( 14 ) for illuminating with an incident light a region on the tooth (T), a detection system ( 16 ) for collecting the light reflected thereat, and an analysis system ( 34 ) for providing a signal to an operator of the probe ( 12 ) when measurements on the reflected light in one or more predetermined range of wavelengths fall within any predetermined range of values that are characteristic of tartar (S). Typically, the detection of tartar (S) is achieved on the basis of the possible colours that tartar (S) can have such that the aforementioned one or more predetermined range of values cover wavelengths associated with colours of tartar (S).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present relates to the detection of dental tartar and, moreparticularly, to the detection of subgingival tartar.

2. Description of the Prior Art

The removal of tartar, for instance with a scraper or a sonic orultrasonic instrument, is important to prevent or to treat periodontaldiseases, i.e. of tissues which surround the teeth, such as bone B, gumsG, ligaments, etc. The tartar is calcified dental plaque that hasaccumulated on the tooth surface. Supergingival tartar and subgingivaltartar S (see FIG. 2) must be removed as tartar is a porous substancewhich contains bacteria and which favours the accumulation of thesepathogenic bacteria on its structure. Moreover, tartar mechanicallyirritates the gums.

In a healthy periodontium (see FIG. 1) there is no periodontal pocket.However, when there is a periodontal disease (FIG. 2), such aperiodontal pocket P is formed by an inner surface of the gums G and bythe root R of the tooth T and which is closed apically by theperiodontal ligaments L. Subgingival tartar S can thus be found in thisperiodontal pocket P.

Therefore, to prevent periodontal problems which can lead to severehealth problems, it is important to remove tartar from the tooth surfaceas it is forming; on the other hand, the removal of tartar is done withdifficulty and in a groping manner, subgingival tartar being normallyinvisible to the human eye in normal conditions as it is covered by thegums. To remove subgingival tartar (i.e. located behind the gum), theoperator must try to locate tartar by tactile feeling using a probe, butone cannot actually view subgingival tartar to ensure a complete removalthereof without resorting to invasive surgical procedures.

The use of an endoscopic method and device for the removal ofsubgingival tartar is also known from U.S. Pat. No. 5,230,621 and No.5,328,365. In this system, an endoscopic probe is inserted in thegingival pocket or sulcus to endoscopically visualise the process ofand/or effects of subgingival root planing, scaling or other plaqueremoval procedures carried out by other operative instruments.Alternatively, the endoscopic viewing apparatus may be incorporated inan operative instrument which itself is used to remove depositedmaterial from subgingival tooth surfaces, whereby the operator may viewand/or guide the instrument while using the plaque removal instrumentitself. Therefore, the operator looks at a monitor that provides imagesof the endoscopic viewing and the operator detects the presence ofsubgingival tartar by looking at the monitor. This system is efficient,but somewhat cumbersome to use as the operator must stop looking intothe mouth of the patient in order to look at the monitor. Moreover, thissystem is relatively expensive, as it requires a monitor and associatedhardware.

Therefore, there is a need for a dental instrument which, using a probeor the like, can automatically detect the presence of subgingivaltartar, which does not require the use of a monitor, and which allowsthe operator to concentrate on his/her task in the patient's mouth bynot having to look at a monitor and thus leave the patients mouth fromhis/her sight. Such an instrument would facilitate the operator's taskof removing subgingival tartar by providing a system which assists theoperator in the diagnostic.

SUMMARY OF THE INVENTION

It is therefore an aim of the present invention to provide a novelsystem for the detection of dental tartar, including subgingival tartar.

It is also an aim of the present invention to provide a novel system forthe detection of dental subgingival tartar that automatically detectsthe tartar based on its spectral reflectance characteristics (of whichcolour is a special case).

It is a further aim of the present invention to provide a system inwhich a visual, sound-based, or other, signal is given followingdetection of subgingival tartar, wherein this detection results frommeasurements made in the subgingival region and taken in one or morepredetermined ranges of wavelengths that are appropriate fordiscriminating the spectral reflectance characteristics that constitutea signature of tartar presence.

Therefore, in accordance with the present invention, there is provided adental tartar detection system, comprising a probe adapted to bedisplaced along a tooth, illumination means for illuminating with anincident light a region on the tooth, detection means for collecting thelight reflected thereat, and an analysing system for providing a signalto an operator of said probe when measurements on the reflected light inone or more predetermined ranges of wavelengths fall within any firstpredetermined range of values that are characteristic of tartar, or whensaid measurements do not fall within any second predetermined range ofvalues that are characteristic of artefacts other than tartar.

Also in accordance with the present invention, there is provided amethod for removing dental tartar from teeth, comprising the steps of:(a) providing an incident light on a region of a tooth, (b) collectingand measuring reflected light from said region of the tooth; (c)analysing said reflected light to determine if said reflected light isrepresentative of the presence of tartar; and (d) providing a signal toan operator of a tartar removal apparatus when presence of tartar hasbeen detected in step (c).

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus generally described the nature of the invention, referencewill now be made to the accompanying drawings, showing by way ofillustration a preferred embodiment thereof, and in which:

FIG. 1 a is a schematic vertical cross-sectional view of a tooth and itssurrounding tissues;

FIG. 1 is an enlarged view of bubble 1-1 of FIG. 1 a;

FIG. 2 is a schematic view similar to FIG. 1 but showing a periodontalpocket between the tooth's root and the gums, with subgingival tartarbeing shown lodged therein;

FIG. 3 is a schematic representation of a system for the detection ofdental tartar in accordance with the present invention;

FIGS. 4 and 4 a are schematic enlarged partial detailed views of thedetection system of FIG. 3;

FIG. 4 b is a schematic detailed view of some components of the casingof FIG. 3;

FIG. 5 is a view similar to FIG. 2 but showing the detection ofsubgingival tartar in the periodontal pocket using the system of thepresent invention; and

FIGS. 6 a, 6 b and 6 c are schematic views of three methods forcombining a number of light beams and coupling them into one or moreoptical fibres.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is a system 10 for the automated detection of thepresence of subgingival tartar S with an endoscopic-like explorationdevice using an optical method based on the spectral reflectanceproperties of tartar to discriminate the tartar present on the teethfrom the healthy areas thereof, from the gums, from blood, and in factfrom any artefact other than tartar that a probe may encounter when itis inserted between a tooth and the gums.

More particularly, the system 10 comprises three main mechanisms, thatis (1) a buccal probe, (2) a casing containing optical components, lightsources, and acquisition and signal processing electronics, as well as awater inlet capable of being connected to a water supply, and (3) acable strand that includes optical fibres and a water supply tube andwhich connects the probe to the casing.

Indeed, the system 10 comprises a periodontal probe 12, containingoptical fibres and, more particularly, one or more illumination fibres14 used for illuminating the subgingival region and one or moredetection fibres 16 for receiving the light reflected by the tooth T forthe subsequent determination of the spectral reflectance characteristicsin this region. It is contemplated that a single optical fibre could beused for both illumination and detection functions. The probe has acurved pointy end section 60 with the illumination fibres 14 anddetection fibres 16 being contained in the pointy end section 60 andextending up to an open free or distal end 36 thereof and having theirrespective distal ends thereat.

The probe 12 includes a handle 18 and may include an attachmentmechanism 20 so that it may be installed on various apparatuses A usedfor removing dental tartar S by way of ultrasounds or any other suitableremoval technique. It is possible to incorporate the spectralreflectance detection technique described herein which uses fibre opticstechnology in such tartar removing instruments A to further integratetogether the diagnostic and the treatment in a single instrument. Theprobe 12 also includes a connector on the proximal end of the handle 18and an irrigation micro-system 22 to clean the site, that is thesubgingival region, by injecting water in the periodontal pocket P, inorder to provide for further detection efficiency.

The irrigation micro-system 22 includes communicating first and secondwater supply tubes 24 and 26, respectively, a valve 28 on the firstwater supply tube 24 and water source 30. The second water supply tube26 extends through the handle 18 with a distal section thereof 19 (madeof stainless steel or other biocompatible material, e.g. plastic orother) extending outwardly of the handle 18. The distal section 19 ofthe second water supply tube 26 extends out of the handle 18 along thecurved pointy end section 60 and terminates short or upstream of thedistal end 36 of the curved pointy end section 60 and thus also of thedistal ends of the illumination and detection fibres 14 and 16 such asto project water to the distal end 36 of the probe 12 so that blood orany other debris can be evacuated therefrom.

A cable strand 32 links the probe 12 to an electronic system that isprovided in a casing 34 which could have the shape and size of aportable cassette player (i.e. a Walkman™) which would be adapted to beconnected to an outside power supply (unless the casing 34 may bepowered with batteries placed in it) and to the water source 30, therebyrendering the system 10 portable. The light propagated by distalsections of the illumination and detection fibres 14 and 16 in the probe12 is thus further conveyed to or from the casing 34 by proximalsections of these fibres 14 and 16 that are part of the cable strand 32.The cable strand 32 carries and protects the illumination and detectionfibres 14 and 16 and the first water supply tube 24. The cable strand 32is detachably connected to the connector provided at a proximal end 33of the handle 18 of the probe 12 so that the probe 12 can be detachedfrom the cable strand 32 for allowing the probe 12 to be sent alone toan autoclave for its sterilisation. The probe 12 could also be of thesingle-use type and would thus be discarded instead of sterilised.

Each of the one or more illumination fibres 14 provided to illuminatethe site (i.e. the periodontal pocket P) has one of its extremitiesfacing a light source (which may be provided or not with an opticalwavelength selective filter) and its other extremity at the distal freeend 36 of the probe 12. Each such fibre 14 is interrupted (or sectioned)at the connector between the cable strand 32 and the probe 12.

Each of the one or more detection fibres 16 (which may be the same oneas that or those optical fibres 14 used for illuminating the periodontalpocket P) is used for receiving the reflected light coming from theperiodontal site. Each such detection fibre 16 has one of itsextremities at the distal end 36 of the probe 12 and its other extremityfacing a photodetector (or an electronic light transducer) 38 (which mayor not comprise an optical wavelength selective filter). Each such fibre16 is interrupted (or sectioned) at the connector between the cablestrand 32 and the probe 12.

This detector 38 is connected to an electronic system housed in thecasing 34.

At the detector or from the signal delivered by the detector, there maybe an electronic or physical (optical) filtration system to remove fromthe received wavelengths those that result from non-tartar structures.The signal obtained after this filtering is then analysed by anelectronic processor to determine whether tartar is present at thedistal end 36 of the probe 12 or not.

If tartar is detected, an indicator (luminous, sound, or any other meanssensible by the operator) is actuated so that the operator is informedof the presence of tartar in the region being examined by the distal endof the probe 12. For instance, the indicator can take the form of aluminous indicator 42 located on the probe 12 to which light generatedin the casing 34 is conveyed by one or more optical fibres 44 betweenthe casing 34 and the handle 18 of the probe 12 such as to terminate atthe indicator 42 provided on the handle 18, and such that the operatorcan see the light conveyed by the optical fibres 44 upon detection oftartar. Also, the luminous signal could come from a warning LED (lightemitting diode) positioned on the handle 18 and electrically connectedto a switch located in the casing 34 and triggered automatically upondetection of tartar.

A connector 46 at the end of the cable strand 32 provides a detachableconnection mechanism between the handle 18 of the probe 12 and the cablestrand 32 (see FIGS. 4 and 4 a). The cable strand 32 is again a flexiblesheath for the illumination and detection optical fibre(s) 14 and 16,the first water supply tube 24 and the optical fibre(s) 44 for theluminous indicator 42 on the probe 12, if any.

The casing 34 includes an electrical input power supply 48 (the powersupply can be internal or external), one or more light sources 50(halogen bulb, laser or diode) which may be or not filtered by anoptical wavelength selective filter, the photodetector 38, an electronicprocessor and memory chip with an input for an electronic card 40 (whichcould serve for example to store information), or the like, aninterrupter or switch 54, and a speaker 56 with an amplifier 58 to emitsounds to warn the operator of the presence of tartar.

The valve 28 is provided on the first water supply tube 24, the latterbeing flexible and being connected at one end thereof to the handle 18of the probe 12 and at another end thereof to the water source 30. Thevalve 28 allows for the flow of water to be adjusted.

Therefore, the system 10 can transmit light having an appropriatespectral composition via the illumination fibre(s) 14 onto the tooth'ssurface and can retrieve the light reflected by the tooth's surface viathe detection fibre(s) 16 which may, or not, be distinct from theillumination fibre(s) 14. This reflected light is then detected by aphotodetector present in the casing 34 such as to be analysed. Dependingon how the spectral composition of the incident light is altered by thereflection thereof on the tooth's surface, an algorithm allows todetermine from the photodetector signal if the probe 12 is viewing, ornot, tartar. Therefore, if the spectral composition of the reflectedlight falls within the range or ranges previously determined for dentaltartar, the algorithm sends a sensory signal to the operator, such as byactuating the luminous indicator 42 on the handle 18 via the opticalfibre 44 which conveys light generated in the casing 34 to the indicator42, although the signal could also be given in the form of sound,vibration, etc.

With reference particularly to FIG. 4 b, the illumination fibre(s) 14 is(are) used to carry light from two LEDs 62 and 64, having differentemission spectra and located in the casing 34, up to the distal end 36of the probe 12. The light emitted by the two LEDs and 64 is coupledinto the illumination fibre(s) 14 and, for this coupling, a dichroicmirror is used, also called a dichroic beamsplitter, as it is selectivein wavelengths in transmitting light to pass within a range ofwavelengths while reflecting light in another range of wavelengths. Sucha dichroic mirror or dichroic beamsplitter is also called hot mirror orcold mirror, depending on the wavelength ranges for which the mirror isreflective or transmissive. A set of lenses in a “Y” configuration, orany suitable means, may also be used instead of the dichroic mirror ordichroic beamsplitter to combine the light beams emitted by the LEDs 62and 64 and couple them into the illumination fibre(s) 14. In FIG. 4 b,which illustrates the coupling in the illumination fibre 14, numeral 66refers to lenses while numeral 68 is for the dichroic beamsplitter whichis at 45° and which transmits the light in the wavelength range emittedby LED 62 and reflects the light in the wavelength range emitted by LED64.

The LEDs 62 and 64 are chosen based on the spectral bands in which thereflectance properties of tartar are different from the reflectanceproperties of the other artefacts which could possibly be encountered bya probe inserted between a tooth and its gum (healthy parts of the toothand gum), and this even when blood is present. In fact, in thesespectral bands, the spectral transmission of blood has minimal effect.The choice of the spectral bands was determined by a spectral study efthe reflectance properties of tartar for the wavelength range of theelectromagnetic spectrum between 400 nm and 1,000 nm. This spectralstudy was conducted in the presence and in the absence of blood. LED 62emits in the red area of the spectrum and its emission spectrum has itspeak at approximately 625 nm and extends from 600 nm to 650 nm. For LED64, its emission spectrum extends between 800 nm and 920 nm. The LEDs 62and 64, or any other appropriate light source, could also operate withother wavelengths that are appropriate for the discrimination of tartar,such as in the green region of the spectrum.

With respect to the detection principle used in the present system 10,it operates on the basis of the following. The light reflected by thetooth T is received by the detection fibre 16 and is conveyed to aphotodiode located in the casing 34 so as to be transduced into anelectric signal. The electronic detection of the light reflected by thetooth and transmitted by the detection fibre(s) 16 operates under the“lock-in” detection principle (also referred to as phase-sensitivedetection), although other signal processing approaches could becontemplated. Generally, this principle consists in modulating theintensity of a light source at a given and known modulation frequency(which should not be confused with the optical frequency of the lightsource). The modulated light is sent onto the medium being inspected andthe light, resulting from the interaction with the medium, is detectedwith a photodetector that converts it into an electric signal. Thiselectric signal is then demodulated such as to extract therefrom onlyits component having the frequency at which the light source wasmodulated. This principle allows for the detection of very small signalswith great efficiency.

In the system 10, there are two light sources (i.e. the LEDs 62 and 64,although there could be more or less, e.g. 3 LEDs) that are modulated atdifferent frequencies, thereby permitting the detection of the lightemitted by both LEDs with a single photodiode by demodulating theelectric signal of the photodiode at the two modulation frequencies ofthe LEDs to obtain a measurement of the amount of the light reflected bythe tooth in the two spectral bands associated with the LEDs 62 and 64.These levels appear as signals V1 and V2 at the outputs of the twolock-in circuits associated with the emission channels of the LEDs 62and 64, respectively, and are used by the processing algorithm. Thelock-in detection is herein used for two purposes: (1) it allows toelectronically separate (at the detection) the light of both chosenspectral bands impinging on a single detector, and (2) the light levelsreflected by the tooth and then detected are very weak and the lock-inmethod is exploited for its sensitivity.

The signals V1 and V2 at the exits of the lock-in circuits are processedin real time by an electronic processor integrated with the rest of theelectronic components of the casing 34. The processing algorithm isprogrammed in this processor. The processing algorithm produces theratio of these two signals V1 and V2, y=V1/V2 (the order in which thisratio is taken is irrelevant). If this ratio is in a range of valuesassociated with tartar (this range having been previously establishedusing calibration measurements), then the probe 12 is located on tartar.In this case, the algorithm sends a signal to activate a warning sound(that can be deactivated by the operator, if desired) and to activatethe warning LED in the casing 34 with the light of the warning LED beingtransmitted through the optical fibre(s) 44 and being visible throughthe indicator 42 located on the probe handle 18.

To determine the range of values of the ratio y associated with tartar,a large number of measurements are taken on teeth at various healthylocations thereof and where there is tartar, and this with differentlevels of blood. By knowing, for each of these measurements, if it wastaken on a healthy part or where there is tartar, data are obtained foreach of these two situations. By bringing the histograms of these dataon a graphic, the range of values associated with tartar is determined.

In use, the operator mounts the probe 12 of the system 10 of the presentinvention on the tartar removing apparatus A (although both thedetection system 10 and the removal apparatus A could be kept separatefrom each other during their use). The operator (1) uses the probe todetermine where there is tartar and then (2) proceeds to removing thetartar in a conventional manner in regions where tartar has been sodetected. The operator then (3) verifies with the probe 12 that theremoval of subgingival tartar is complete, and steps (2) and (3) arethen repeated until no tartar is detected. To locate tartar with thepresent detection system 10 in both the above steps (1) and (3), theoperator inserts the end section 60 of the probe 12 behind the gum G(i.e. in the periodontal pocket P). The operator then slides the freedistal end 36 of the end section 60 of the probe 12 against the surfaceof the root R of the tooth E, sweeping this surface. The operator mustalso ensure adequate supply of water to the root R of the tooth E byadjusting the position of the valve 28, which may be manually operatedvia a foot pedal or a control provided on the handle 18 of the probe 12.When the operator receives a sensory stimulation or signal (e.g. fromthe illumination of the optical fibre 44, through the indicator 42, orany other means of indication in replacement or in addition to theindicator 42, such as a buzzer, vibrations, etc.) from the electronicsystem, the operator knows that there is some subgingival tartar at thelocation of the distal end 36 of the probe 12 and thus visually notesthe position of the distal end 36 of the probe 12 such that the operatorcan then proceed with step (2) which again consists in using the tartarremoving apparatus A, for removing the remaining tartar at thatlocation.

Here, for coupling the light from the LEDs 62 and 64, a particularapproach has been presented using a dichroic mirror and lenses, but anyother configuration, such as a “Y” configuration, which allows to couplethe light from the LEDs into the fibres would do as well, thefundamental point being the coupling of light into the fibres.

For instance, FIG. 6 a illustrates a coupling 100 by fusion of twooptical fibres 102 and 104 into a single fibre 106. Two LEDs 108 and 110are used, each emitting light through a pair of lenses 112 and 114.Reference numeral 116 denotes a fused region. This method iscommercially known as a WDM coupler.

FIG. 6 b illustrates another coupling 200 which uses a “Y” configurationto couple the two lights. More particularly, two LEDs 202 and 204 arepositioned each behind a pair of lenses 206 and 208 such as to emitlight therethrough. The lenses 206 and 208 focalise the light on theextremity of an optical fibre 210. Reference numeral 212 denotes theoptical axis of the fibre 210.

FIG. 6 c illustrates a further coupling 300 which also uses a “Y”configuration but here to couple four lights that are produced by fourLEDs 302, 304, 306 and 308 positioned each behind a pair of lenses 310and 312 such as to emit light therethrough. The lenses 310 and 312focalise the light on the extremity of an optical fibre 314. Referencenumeral 316 denotes the optical axis of the fibre 314. It is noted thatin a further coupling, also in a “Y” configuration, there could be threeLEDs instead of the two and four LEDs found respectively injust-described couplings 200 and 300 of FIGS. 6 b and 6 e.

Also, as regards the detection principle described above (i.e. thelock-in detection), other principles could be used as well. Any approachthat can deliver signals that are sufficiently insensitive to noise toprovide for discrimination between tartar and other artefacts that canbe found in a periodontal pocket P can be considered. Furthermore, in anumeric system, there could be used for instance two LEDs havingdifferent wavelengths (but possibly of same frequency), e.g. a red and agreen LED, which are activated repeatedly one after the other and with adelay therebetween.

As an alternative to the processing algorithm presented hereinabove,combinations of the signals V1 and V2 other than the above ratio y couldbe considered. Indeed, the classification of the data into “is tartar”and “is not tartar” could be done in a two-dimensional space, forinstance by plotting V1 versus V2, or any other function of V1 and V2versus another function of V1 and V2 that is independent from theprevious function. Also, if more than two LEDs or other sources of light(such as lasers, halogen lamps, spectral lamps, filtered lamps, etc.)are used, information can be gathered and analysed in two or moredimensions.

Furthermore as an alternative to the approach just described, aspectrometer could be used to measure a spectrum of the light reflectedby the tooth and this spectrum would then be analysed with an algorithmto determine if it corresponds to a spectrum of tartar or to a spectrumof another artefact. Any other suitable method may be used to analysethe spectrum received and compare it with the spectrum of tartar with aview to detecting the presence of tartar.

The present system could, by varying the spectrum to be detected, beused to locate other structures having distinctive spectralcharacteristics and positioned in a buccal site where access is limited(e.g. dental decay).

The system 10 could also include a recalibration function. A warningsignal can also be provided to indicate when too much blood is presentin the area being examined by the probe 12 and that the system 10 cannotmake an adequate reading and thus cannot determine with sufficientprecision if tartar is present on the tooth in this area.

A further feature could be included to indicate if the probe 12 or, morespecifically, the illumination and/or detection fibres 14 and 16 thereofare too worn out to be efficiently used and should thus be replaced.Such a state could be detected by insufficient light being received inthe electronic system provided in the casing 34.

In addition to providing to the operator the luminous (or other) signalthat indicates the presence of tartar with an indicator (such as theillustrated optical fibre 44), the system 10 may also include a monitorthat displays further information to the operator such as electronicsignals within the system which would help his/her diagnostic.

There may also be included a means of collecting data from theelectronic system (e.g. via a computer and software, including anelectronic card 40, etc.), to be saved in any kind of storing medium forallowing the patient's history to be followed.

For the present embodiment of the system 10, the reflectance propertiesof tartar in the range between 400 nm and 1,000 nm have been studied,and light sources in that range are used (the two LEDs 62 and 64).However, use of light sources emitting below 400 nm in the ultraviolet(UV) range or above 1,000 nm in the far infrared could also beenvisaged.

Also, as the spectral responses of various artefacts other than tartarare known, such as those of enamel, of the tooth's root surface, of thegum, of blood, of tooth decay (caries), of tooth fillings, etc., it ispossible to adapt, e.g. program, the system 10 so that a tartar-presencesignal is given to the operator as a result of the detection of spectralcharacteristics that are not representative of those of theaforementioned artefacts. Therefore, if the system 10 detects onlyspectral characteristics of these artefacts (wherein the term“artefacts” herein excludes tartar), there is no tartar in the regionunder examination.

As tartar does not respond to UV light, whereas other artefacts do, ifUV light is directed onto the tooth, absence of fluorescence may be anindication of the presence of tartar.

Also, a tracing substance could be used, which would adhere to tartarbut not to other artefacts. By then illuminating the tooth with a lightsource, the tracing substance would emit at a specific wavelength suchthat if this wavelength is detected, tartar is present. It is alsopossible to use a substance which reacts with the components of tartarsuch that a spontaneous emission of light at a specific wavelength isemitted. This spontaneous emission of light is collected with theoptical probe. If the specific wavelength is detected, there is tartar.This method may possibly be used without a light source at the patient'smouth.

It is also possible for the tartar to be detected using non-luminouswavelengths or by other similar methods, e.g. far infrared, ultraviolet,piezoelectric, ultrasound, magnetic resonance, shadows, etc.

Means other than optical fibres may be used to illuminate the teeth andto collect light reflected therefrom as long as the reflected light isof sufficient intensity to allow it to be analysed.

The illumination fibres 14 and detection fibres and second water supplytube 26 could, instead of being part (downstream of the connector whichconnects the cable strand 32 to the handle 18) of the probe 12, beincorporated within a tartar removing instrument (using ultrasounds orother means) to further integrate together the tartar detection andremoval processes. In such a case, the combined detection and removalinstrument would include a switch for alternating between the tartardetection and tartar removing modes. Such a switch could be actuated bythe operator or be actuated automatically for switching between theabove two modes at an adjustable frequency, e.g. every 1/15 to 1/100second. The combined detection and removal instrument could thus bedisplaced along the tooth while removing the tartar therefrom andindicating, for instance with a luminous or sound-based indicator, thepresence of remaining tartar. This would continue until the indicator ofthe detection system of the instrument is not actuated.

1. A dental decay detection system, comprising a probe adapted to bedisplaced along a tooth, a light source for illuminating with anincident light a region on the tooth at two wavelengths including onewavelength in the infrared range, a spectral reflectance light intensitydetector and analyzer for collecting the light reflected thereat andproviding a signal to an operator of said probe when measurements on thereflected light in one or more predetermined ranges of wavelengths fallwithin any first predetermined range of values that are characteristicof said dental decay, or when said measurements do not fall within anysecond predetermined range of values that are characteristic ofartefacts other than dental decay.
 2. A dental decay detection system asdefined in claim 1, wherein said first predetermined range of valuescover wavelengths associated with spectral reflectance characteristicsof dental decay.
 3. A dental decay detection system as defined in claim1, wherein said probe comprises a distal end with said illumination anddetection means terminating substantially adjacent said distal end.
 4. Adental decay detection system as defined in claim 3, wherein said lightsource and said spectral reflectance detector comprise at least oneoptical fibre having a distal end located adjacent said distal end ofsaid probe, said light source being at a proximal end of said opticalfibre such that said incident light emitted by said light source istransmitted by said optical fibre to said distal end thereof and to thetooth.
 5. A dental decay detection system as defined in claim 1, whereinsaid predetermined range of values cover wavelengths associated withcolours of dental decay.
 6. A dental decay detection system as definedin claim 1, wherein said predetermined range of values cover wavelengthsassociated with colours of dental decay.
 7. A dental decay detectionsystem as defined in claim 6, wherein said analysing system is adaptedto analyse said reflected light and providing said signal.
 8. A dentaldecay detection system as defined in claim 4, wherein said light sourceand said detector each comprises one said optical fibre, said distal endof each said optical fibre being located adjacent said distal end ofsaid probe. 9-13. (canceled)
 13. A dental decay detection system asdefined in claim 8, wherein said optical fibres comprise proximalsections that are detachably connected to said distal sections forallowing said distal sections and said probe to be selectively detachedfrom said proximal sections for discarding said distal sections and saidprobe and replacing with new ones, or for sterilising said distalsections and said probe before being returned to said proximal sectionsfor further use thereof.
 14. A dental decay detection system as definedin claim 1, wherein said light source and said detector compriseproximal and distal sections that are detachably connected together forallowing said distal sections and said probe to be selectively detachedfrom said proximal sections for discarding said distal sections and saidprobe and replacing with new ones, or for sterilising said distalsections and said probe before being returned to said proximal sectionsfor further use thereof. 15-21. (canceled)
 22. A dental artefactdetection system, comprising a probe adapted to be displaced along atooth, a light source for illuminating with an incident light a regionon the tooth at two wavelengths including one wavelength in the infraredrange, a spectral reflectance light intensity detector and analyzer forcollecting the light reflected thereat, and providing a signal to anoperator of said probe when measurements on the reflected light in oneor more predetermined ranges of wavelengths fall within any firstpredetermined range of values that are characteristic of a first dentalartefact, or when said measurements do not fall within any secondpredetermined range of values that are characteristic of artefacts otherthan said first dental artefact, wherein said signal is an indicatorlocated substantially at a position of the distal end of said probe andactuated by said analyzer to indicate to the operator the presence ofsaid dental artefact.
 23. A dental artefact detection system as definedin claim 22, wherein said indicator comprises at least one of aluminous, a sound and a vibratory indicator.
 24. A dental artefactdetection system as defined in claim 22, wherein said indicator isprovided on said probe and comprises an optical fibre extending betweensaid detection means and said probe for providing a luminous indicatoron said probe when said dental artefact has been detected by saiddetector.
 25. A dental artefact detection system as defined in claim 44,wherein said monitor is adapted to show a schematic or graphicrepresentation of a broad range of wavelengths with boundariesrepresentative of said predetermined range of values being indicated onsaid representation, said monitor also being adapted to show readings ofsaid reflected light on said representation such that positions of saidreadings thereon relative to said boundaries are indicative of thepresence or absence of said dental artefact. 26-29. (canceled)
 30. Amethod for detecting dental decay on teeth, comprising the steps of: (a)providing an instrument adapted for directing incident light on a regionof a tooth at two wavelengths including one wavelength in the infraredrange, (b) collecting and measuring reflected light from said region ofthe tooth; (c) analysing said reflected light to determine if saidreflected light is representative of the presence of said dental decay;and (d) providing a signal to an operator of said instrument whenpresence of said dental decay has been detected in step (c).
 31. Amethod as defined in claim 30, wherein measurements determined in step(b) are analysed in step (c) for comparison with any predetermined rangeof values that are characteristic of dental decay.
 32. A method asdefined in claim 31, wherein said predetermined range of values coverwavelengths associated with spectral reflectance characteristics ofdental decay.
 33. (canceled)
 34. A method as defined in claim 30,wherein an illumination system used in step (a) and a detection systemused in step (b) comprise at least one optical fibre having a distal enddisplaced adjacent the tooth, said illumination system also comprising alight source at a proximal end of said optical fibre such that saidincident light emitted by said light source is transmitted by saidoptical fibre to the tooth whereat said reflected light is transmittedby said detection system to an analyzer for analysing said reflectedlight and providing said signal. 35-38. (canceled)
 39. A method asdefined in claim 4, wherein said at least one optical fibre comprises aproximal section that is detachably connected to said distal section forallowing said distal section and said probe to be selectively detachedfrom said proximal section for discarding said distal section and saidprobe and replacing with new ones, or for sterilising said distalsection and said probe before being returned to said proximal sectionfor further use thereof.
 40. A method as defined in claim 30, wherein instep (d) said signal is provided in the form of at least one of a light,a sound and a vibration.
 41. A method as defined in claim 40, wherein instep (d) said signal is extracted from a monitor means adapted to show aschematic or graphic representation of a broad range of wavelengths withboundaries representative of one or more predetermined range ofwavelengths representative of the presence of dental decay beingindicated on said representation, said monitor means also being adaptedto show readings of said reflected light on said representation suchthat positions of said readings thereon relative to said boundaries areindicative of the presence or absence of dental decay.
 42. A method asdefined in claim 30, wherein measurements determined in step (b) areanalysed in step (c) for comparison with any predetermined range ofvalues that are characteristic of artefacts other than dental decay thatcan be encountered by said probe along the tooth such that when saidmeasurements do not fall within said predetermined range of values, saidsignal in step (d) is sent to the operator.
 43. (canceled)
 44. A dentalartefact detection system as defined in claim 22, wherein said indicatoralso comprises a monitor adapted to display further information to theoperator, said information including electronic signals which may beuseful in detecting said dental artefact.
 45. A dental artefactdetection system as defined in claim 22, wherein said artefact is one oftartar and dental decay.